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From "Henderson, Roy" <Roy.Hender...@eu.weatherford.com>
Subject RE: accessing records problem
Date Mon, 10 Feb 2014 09:26:47 GMT
Should it not perhaps be while(k < 100) since you start from 0 and post-increment?

What value does k have when you get the NPE?

-----Original Message-----
From: Bob M [mailto:rgmatthews@orcon.net.nz]
Sent: 10 February 2014 09:20
To: derby-user@db.apache.org
Subject: accessing records problem

Hi

I am calling derby within a larger java program....................

Step1: I allocate a database "Connection" object
Step2: I allocate a "Statement" object in the connection
Step 3: I execute a SQL SELECT query, the query result is returned in a
"ResultSet" object
so far so good (I update the latest database record, I add a new record and
I delete the oldest record
I then call a data mining program [Weka]
I setup a few Weka models etc......
I then wish to look at the last 100 records in my database, one at a time
The code I have currently is as follows:-
***********************
try {
Statement s = null;
ResultSet rs = null;
rs = s.executeQuery ("SELECT".................);
int k = 0
while (k < 101) {
rs.next();
...
...
}
k++;
}
}
catch (Exception e)
{
myConsole.getOut().println(e);
}

I get the following error:-
java.lang.NullPointerException

do I need to do something further to read my 100 records?

Bob M




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